Sliding Window Frame Mechanism for Consistent Sash Force
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Solution Overview
Problem
Sash window assemblies face issues with force variation in spiral balance systems, leading to insufficient force at extremities, misorientation during rotation, and increased wear due to metal arms, which can cause damage and unsightly wear of protective coatings.
Innovation Solution
A frame with a sliding mechanism featuring a first and second track coupled via a rotary coupling member, allowing the closure element to slide relative to the frame, and a gas spring to modulate the force required, along with a cord and bolt mechanism to arrest rotation and inhibit movement, ensuring smooth operation and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spiral balance system is used to enable the sash to be easily moved, then the force required to lift the sash is reduced, but the force varies during travel and becomes insufficient at extremities
Solution Approach 1:
The patent uses a spiral rod with varying pitch to change the mechanical parameters during travel. The pitch increases as the sash rises, which changes the mechanical advantage dynamically to compensate for the changing weight distribution and maintain consistent lifting force throughout the full range of motion.
Solution Approach 2:
The spiral balance system is a dynamic mechanism where the pitch of the spiral rod changes continuously during operation. This dynamic adjustment of the screw thread pitch allows the system to adapt the mechanical advantage ratio throughout the travel, ensuring consistent force application rather than relying on a fixed ratio.
2Ease of operation
If an expanding shoe within a track is used to inhibit sash movement when rotated, then the sash can be held in rotated position, but the frictional force is insufficient at partial rotation angles causing slippage
Solution Approach 1:
The patent removes the expanding shoe mechanism from the system and replaces it with a cord and reel mechanism. This extraction of the problematic friction-based holding mechanism eliminates the slippage issue while maintaining the ability to hold the sash in rotated positions through a different physical principle (tension in the cord).
Solution Approach 2:
The patent replaces the friction-based expanding shoe mechanism with a cord and reel system. This substitution changes the holding mechanism from relying on friction (which varies with rotation angle) to relying on cord tension, which can be maintained consistently through the reel mechanism regardless of the sash rotation angle.
3Ease of operation
If metal arms are used to arrest rotation of the sash, then the rotation can be controlled, but additional wear occurs on the frame and sash during rotation
Solution Approach 1:
The patent replaces the metal arm rotation control mechanism with a cord and reel system. This substitution eliminates the metal-to-metal contact that causes wear during rotation, while still providing effective rotation control through the cord tension mechanism. The cord and reel system reduces friction and wear compared to the metal arm contact system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sliding mechanism provides consistent force throughout the sash travel, prevents misorientation, and reduces wear by stabilizing the sash's movement, maintaining the window's alignment and protecting the frame and sash from damage.
Implementation Method 1
A frame with a sliding mechanism featuring a first and second track coupled via a rotary coupling member, allowing the closure element to slide relative to the frame, and a gas spring to modulate the force required
Data Source
AI summary
A window frame comprising a plurality of elongate frame members defining a frame opening for receiving a window for closing the frame opening. At least one of the elongate frame members having a longitudinally extending recess; and a slide mechanism received within the recess, wherein the slide mechanism comprises a first track fixed within the recess and a second track movable within and along the recess and coupled to the first track via a rotary coupling member such that movement of second track along the recess causes the rotary coupling member to rotate, wherein the second track is arranged to be coupled to the window when the window is received within the frame opening to enable the window to slide relative to the frame.